Help connecting DAC/Headphone Amp to Audio Interface please

[mjv1986]

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Hi, I would greatly appreciate some help with connecting some new hardware. I have a Saffire Pro 14 which is firewired into my Windows 7 PC. I would like to connect an SMSL SD 793II to the setup to drive my headphones.

Back of the Saffire Pro 14: https://sonicscoop.com/wp-content/uploa ... e_back.jpg (https://sonicscoop.com/wp-content/uploads/2010/08/focusrite_back.jpg)

Back of SMSL SD 793II: https://ae01.alicdn.com/kf/HTB1AwSFjol7 ... -96KHZ.jpg (https://ae01.alicdn.com/kf/HTB1AwSFjol7MKJjSZFDq6yOEpXaT/SMSL-SD-793-II-Audio-Optical-Coaxial-DAC-PCM1793-DIR9001-DAC-Digital-Audio-Decoder-24BIT-96KHZ.jpg)

I have a coaxial cable (https://www.amazon.co.uk/AmazonBasics-D ... B01D5H8TS4 (https://www.amazon.co.uk/AmazonBasics-Digital-Audio-Coaxial-Cable-Black/dp/B01D5H8TS4)) and have tried going from SPDIF Out on the Saffire to Coaxial In on SMSL but not able to get any sound out of the SMSL.

Have I got the right cable? Am I missing something/doing it all wrong?

Thanks in advance.

[Septimon]

in your Saffire Mix Control you can route ins and outs, check what is routed to your SPDIF Output.

[mjv1986]

This is what it is currently set at. I'm not sure where the problem is though.

[Septimon]

check with your SMSL SD if it's set to 41,KHz and also if the clock is set to SPDIF. You can also try to set the Sync Source to SPDIF in your Saffire and adjust the Sample Rate to the sample rate in the SMSL if you can't access te settings from your SMSL.
you can also try if it makes a difference if you set the SPDIF Output to "DAW1/2".
The Focusrite support is really helpful. You can use a live chat.

[Septimon]

According to this website your preamp can take up to 24 bit 96 KHz. Probably it just adjusts to what Signal is coming in.
Did you make sure, you selected the correct Input? (Analog/ optical / SPDIF)?
https://m.de.aliexpress.com/item/329307 ... lsrc=aw.ds

[mjv1986]

Thanks a lot for your help, really appreciate it. I think I have tried everything to the best of my technical knowledge (which admittedly isnt great). I have tried the SMSL from RCA to 3.5 and it worked fine so its not the unit itself. But then I'm losing the digital audio side of things through RCA.

Looking closer at the back of the Saffire Pro 14, it looks like the SPDIF In and Out are slightly skewed to the side. I bought this years ago used off eBay and have never needed the SPDIF so maybe there was some damage done in the past. The coaxial lead seems to fit still but maybe there was internal damage. I've fixed headphones before but I'm not going to start opening up an audio interface. Will only make it worse.

Think the best bet would be to buy a USB to Coaxial Converter for the SMSL. Its not ideal but should do the job. Or else buy an new audio interface but seems excessive. Just want the SMSL for listening pleasure to higher impedance headphones. Can still use the Saffire for music production stuff. Do you think a USB to Coaxial Converter would be the best route? Can get one for around 40GBP/50USD. Or are there a lot better audio interfaces out there these days that I could get for reasonable price?

[Septimon]

what's wrong with the Saffire's headphone output concerning higher impedance headphones? (I'm using my saffire with an AKG K 240 DF with 600 Ohm without problems)
Personally i wouldn't spend more money on that headphone preamp but rather get a decent interface if the saffire is not right for you.

[mjv1986]

Well I've got Sony MDR-7506 and can easily have volume at max on the Saffire so I assumed it wasnt particularly powerful. The SMSL is much louder. Got some Hifiman HE4xx on the way so want to be able to properly use them just for pleasurable listening. Which Saffire have you got? Mine is powered only through Firewire. Could a mains supply boost it?

[Septimon]

I have tried the SMSL from RCA to 3.5 and it worked fine so its not the unit itself. But then I'm losing the digital audio side of things through RCA.

Actually you don‘t „loose the digital side of things“ At One point in your signal chain The signal needs to be converted from Digital to Analog. your headphones can‘t be driven by ones and zeros. So the question is: where should the conversion Happen: in your saffire or in your Preamp. I doubt your preamps DA- Converter is better than the Saffire‘s, so using the RCA Input is fine.